How to post ERA payments, from the 835 to a balanced deposit

ERA payment posting is the step where a biller takes the payer’s electronic remittance advice, the X12 835, and records every payment, adjustment, patient balance and denial it reports against the right claim line in the practice management system, then proves the posted total matches the money in the bank. Done line by line, it is the source of every number the practice reports. Done as a lump sum per claim, it hides denials and underpayments inside “paid”.

This guide covers the posting desk from enrollment to month-end. For reading the segments of an 835 one at a time, see the ERA reading guide; for working the denials that posting uncovers, see the denials guide. Both sit with the other billing guides.

What is an ERA, and how does it differ from the deposit?

An ERA is the payer’s electronic statement of how it adjudicated each claim and line on a payment, sent as an X12 835, while the deposit is the money itself, sent separately as an electronic funds transfer, so posting always starts by proving the two belong together. Medicare sends either an ERA or a standard paper remittance after it processes a claim, with the final adjudication and payment information, and issues one check or EFT when payment is due¹.

Medicare’s ERAs are in the 835 version 5010 format adopted as the HIPAA standard, and they explain each adjustment with group codes, claim adjustment reason codes and remark codes¹. The paper remittance carries the same codes plus their text¹.

Two Medicare details change daily habits. Professional providers who receive both formats stop getting the paper remittance after 45 days of receiving ERAs², so a practice that still waits for paper will wait forever. And CMS offers free Medicare Remit Easy Print software that turns an 835 into a readable report for professional providers, updated three times a year with the code lists².

How do you set up ERA and EFT enrollment?

You set up electronic posting by filing an ERA enrollment and an EFT enrollment with every payer that pays you electronically, for each billing NPI and tax ID, and by asking your bank to pass along the reassociation data that links each deposit to its remittance. Without all three, electronic posting falls back to paper and guesswork.

For Medicare, each provider that receives ERAs, directly or through a billing agent or clearinghouse, must sign an ERA enrollment form and file it with the MAC before the MAC will send ERAs³. The provider must also tell the MAC in writing, in advance, about a change of billing agent or clearinghouse and the date it stops using the old one³. Medicare’s contractors include an EFT authorization form in the enrollment package⁴.

The bank step is the one practices skip. The CAQH CORE reassociation rule requires the provider to contact its own financial institution and arrange delivery of the minimum data needed to match each EFT to its ERA: the effective entry date, the amount and the payment-related information field that carries the trace number⁵. Ask the bank in writing which of those fields it passes on, and get the addenda turned on if it does not.

When a practice changes billing companies or clearinghouses, the ERA routing changes too. Put the ERA re-enrollment on the switching plan, with each payer’s effective date, or the first month’s remittances land somewhere nobody is looking.

How do you match each ERA to its deposit?

You match an ERA to its deposit by the reassociation trace number, which the payer puts both in the 835 and in the addenda record of the EFT, and then by amount and date, so that every remittance has one deposit and every deposit has one remittance before anything is posted. Matching by amount alone fails the first time two payments are the same size.

The federal EFT standard places the 835’s trace number segment in a specific addenda field of the bank transfer⁵. The same rule sets the timing window: the payer must release the 835 no sooner than three business days before the EFT effective entry date and no later than three business days after it⁵. That window is why an ERA can arrive before the money or a few days after.

A remittance or deposit that is still missing four business days after its partner arrived counts as late or missing under the CORE rule, and payers must publish written procedures for resolving it⁵. Use that procedure rather than a general phone line. Log the payer, the trace number and the date you asked.

Keep a reassociation list with three columns: matched, ERA without deposit, deposit without ERA. The last two should be short and dated. The month-end routine is in the ERA to bank reconciliation post.

In what order should you post an ERA?

Post an ERA in a fixed order: confirm it balances, post each claim’s lines with their paid amounts and adjustments, move patient responsibility, send zero-paid lines to the denial queue, post the provider-level adjustments, and only then mark the batch complete against its deposit. A fixed order makes errors visible because each step has its own total.

Medicare’s manual sets the balancing rules the order relies on. The check amount is the sum of all claim-level payments less any provider-level adjustments, and a positive adjustment amount reduces the payment while a negative one increases it². Every compliant 835 a MAC issues must balance at the service, claim and provider levels².

1. Balance the file. Add the claim payments, subtract the provider-level adjustments, compare with the payment amount and the deposit. If it does not balance, stop and call the payer before posting a cent.
2. Post line by line. For each claim, find the original claim and each line. Post the paid amount and each adjustment with its group code, CARC and RARC.
3. Move patient balances. Post PR amounts to the patient account by type, so statements can say deductible, coinsurance or copay.
4. Queue the zero-paid lines. A line that paid nothing is a denial or a pending item, not a closed line.
5. Post provider-level items. Recoupments, interest and balance-forward amounts go to their own accounts or to the claims they reference.
6. Close the batch. Posted total equals ERA total equals deposit. Unapplied amounts are listed with a reason.

How do you post each type of adjustment?

Post each adjustment according to its group code, because the group code says who carries the amount: CO is written off under the contract, PR moves to the patient, and OA and PI are neither, so each needs a reason before it is closed. X12’s current group code list has four codes: CO, OA, PI and PR⁶.

Medicare’s manual describes CO amounts as generally a write-off for the provider that is not billed to the patient, and PR amounts as those that may be billed to the patient, typically deductible and copay². CARCs 1, 2 and 3 identify the deductible, coinsurance and copay amounts⁷.

The trap is CARC 45 under CO. It tells you the payer allows less than the practice billed⁷, which is normal, but it does not tell you the allowed amount was right. Post it, then compare the allowed amount with the contract. The CO-45 page and the underpaid claims post show the comparison.

Never close a denial with a contractual write-off code to make a claim balance. A CO-16 line that paid nothing is a correctable claim, and writing it off as contractual removes it from the denial report and from the dollars you can still collect.

What do you do with lines that paid nothing?

Post every zero-paid line at zero with its group code, CARC and RARC, then route it the same day to the denial queue, because the codes on that line are the only record of why the payer said no and the appeal clock is already running from the remittance date. A zero line is not finished work.

Some reason codes are too general to act on alone, and Medicare’s contractors must send at least one remark code with them². Read the pair. Remark codes that begin with “Alert” are informational: they give general adjudication information and can arrive without a group code or reason code². An alert does not need a denial entry; it may need a note.

Separate the zero-paid lines into three piles before they reach the queue: denials with appeal or correction routes, lines bundled into another paid line, and pending items where the payer asked for records. Each pile has a different owner and a different clock.

How do you post provider-level adjustments?

Provider-level adjustments are amounts the payer added to or took from the whole payment rather than a single claim on it, and you post each one to the claim or account it actually belongs to, so that a recoupment reduces the old claim it recovers and not today’s deposit. They sit in the PLB section of the 835.

X12 publishes the provider adjustment reason codes. Four that a physician practice should know by sight are WO for an overpayment recovery, L6 for interest, FB for a balance carried forward that is not tied to a claim, and 72 for a refund the provider sent back⁹.

The PLB line often carries a reference to the claim or letter it relates to. Use it. A WO posted as a loss on today’s batch makes the original claim look fully paid when it was not, and the overpayment letter sits unanswered.

How do you handle reversals and corrected claims?

When a payer reprocesses a claim, the 835 reports the reversal of the original payment and the new adjudication, and you post the net change against the same claim, never the new payment as a second, separate payment. Double posting a correction creates a credit balance that was never real.

Medicare does not issue a remittance for a voided or cancelled claim; it issues one for the adjusted claim, showing as previously paid the amount it paid on the voided one². Read both lines before posting. If the corrected claim pays $20 more than the original, the account moves by $20.

Correct posting matters most on recoupments. A payer that reverses a claim and takes the money back on a later remittance gives you two events on two dates. Link them in the notes so the A/R aging shows one story, not a credit on one date and a debit on another.

How do secondary claims and crossovers affect posting?

After posting the primary payment, a remaining balance either goes to the secondary payer automatically through a crossover or has to be billed by you with the primary’s adjudication attached, and the remark codes on the primary remittance tell you which. Billing a crossed-over claim again creates a duplicate.

When Medicare forwards the claim to a supplemental insurer, the remittance carries remark MA18, an alert that the claim information also went to that insurer⁸. Medicare’s remittance can name only one crossover payer, even if the claim was sent to more than one². A secondary that receives the claim twice may deny the copy as a duplicate of a crossover claim, remark N522⁸.

When there is no crossover, send the secondary claim with the primary’s payment and adjustment data. A secondary payer that never receives that data may deny with MA04, which says it cannot act without the primary’s identity or payment information⁸. The secondary claims post covers the order of operations.

What do you do with credit balances and overpayments?

A credit balance is money on an account that the practice has received but is not owed, and you resolve it by finding the cause, correcting the posting if it was an error, and refunding the payer or patient if it was a real overpayment, inside the deadline that applies. For Medicare, that deadline is set by regulation.

Under 42 CFR 401.305, a provider that has received a Medicare overpayment must report and return it by the later of 60 days after it was identified or the date any corresponding cost report is due¹⁰. The deadline is suspended while the provider conducts a timely, good-faith investigation into related overpayments, until the investigation ends or 180 days after the initial identification, whichever comes first¹⁰. The obligation reaches back six years from the date the overpayment was received¹⁰.

The same rule says to use the MAC’s claims adjustment, credit balance, self-reported refund or other reporting process¹⁰. When the refund is processed, the payer may acknowledge it on a later remittance with PLB code 72⁹. Post that acknowledgment against the refund so the credit closes.

Not every credit balance is an overpayment. Some are posting errors: a reversal posted as a payment, a patient payment posted to the wrong account, a capitation payment posted to a fee-for-service claim. Clear those first, then refund what remains.

How do you know the posting is right?

Posting is right when three totals agree every day, the posted amount, the remittance amount and the deposited amount, when unapplied cash is zero or explained line by line, and when every zero-paid line from the day appears in the denial queue. The checks are quick, and they catch posting errors before the errors reach a report.

At month-end, the deposits in the bank statement should equal the posted payments for the month plus the change in unapplied cash. If they do not, the gap is a deposit without a remittance or a remittance without a deposit, and both are on the reassociation list.

Worked example · hypothetical

A worked example: one Medicare remittance

This is a hypothetical example. A three-physician internal medicine practice receives an 835 from its MAC and an EFT of $1,846.20 with the same trace number. The 835 covers six claims. The claim payments total $1,906.20, and the PLB section shows a WO of $72.00 for an overpayment on a claim paid in March and L6 interest of $12.00.

The biller balances first: $1,906.20 less $72.00 plus $12.00 is $1,846.20, which matches the deposit. Then the lines:

• Four claims paid in full at the Medicare allowed amount, with CO-45 for the difference from the charge and PR-2 for the patient’s coinsurance. The biller checks the allowed amounts against the fee schedule and posts the coinsurance to the patients, three of whom have MA18 on their claims, so the supplemental plan already has the claim.
• One claim has two lines: one paid, one at zero with CO-97, meaning the payer treats it as included in the other line’s payment⁷. The coder reviews the note. It does not support a separate service, so the line is adjusted with the reason recorded.
• One claim paid nothing, with CO-16 and remark M51, the procedure code is the problem^7,8. The line goes to the denial queue with the remittance date and an owner.

The WO is posted against the March claim it references, which now shows a balance of $72.00 that the biller checks against the overpayment letter. The interest goes to the interest account. The batch closes with posted, remittance and deposit totals all at $1,846.20, no unapplied cash, and one new denial in the queue.

When should a billing team take over payment posting?

Hand payment posting to a billing team when remittances sit unposted for days, when unapplied cash grows from month to month, or when the person posting also answers the phones and works the denials. A dedicated remote biller can match every ERA to its deposit, post line by line by group code, send zero-paid lines to the denial queue, and reconcile the month to the bank.

Remitwright’s payment posting service works this way: a dedicated biller per client (or a dedicated team for larger groups), working remotely in the client’s own practice management system and clearinghouse. The decisions about refunds and write-offs above the practice’s limit stay with the practice owner.

Posting is the least visible billing job and the one every report depends on. If the posting is wrong, the denial rate, the days in A/R and the collection rate are all wrong with it.

Checklist

ERA posting checklist

1. Every payer that pays electronically has an ERA enrollment and an EFT enrollment on file for each billing NPI and tax ID
2. The bank delivers the trace number and addenda with each EFT so deposits can be matched to remittances
3. Each 835 is matched to its deposit by trace number before any line is posted
4. The remittance total is checked against the sum of claim payments less provider-level adjustments
5. Paid amounts and adjustments are posted at the line level, not as a lump sum per claim
6. CO amounts are written off only when the allowed amount matches the contract or fee schedule
7. PR amounts move to the patient balance with the deductible, coinsurance and copay split kept
8. Zero-paid lines go to the denial queue with group code, CARC and RARC the same day
9. Recoupments, interest and balance-forward items are posted to the claim or account they belong to
10. Reversals and corrected claims are posted as a net change, never as a second payment
11. Crossover claims are not billed to the secondary payer a second time
12. Unapplied cash is cleared or explained every day, and every deposit ties to a posted remittance
13. Credit balances are reviewed against the 60-day Medicare overpayment rule and refunded through the payer's process

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